*** Good Night, Mr. Holmes, Carole Nelson Douglas, 1990
It's been a while since I've read an extra-canonical Holmes novel I liked this much. While this is not really a Holmes story, since it's the story of Irene Adler, it does involve Holmes in very important, if occasional, ways. In addition, the style fits very well with the canon.
Douglas's writing is excellent. There were one or two words in the 400+ pages that I would have changed if it were me, but that's just plain being picky at this point.
The story is engaging and well paced, characters are brilliant, well, there's just not much more to say. It's great.
Highly recommended (4 stars) for Holmes fans, recommended for everyone else.
I have a couple more in the series on the shelf. Can't wait to read them.